A conventional adjusting device for longitudinal adjustment of a vehicle seat comprises an upper rail, which supports the vehicle seat, and a lower rail, which is usually fixed to the bottom of the passenger compartment of a vehicle. The upper rail can be adjusted relative to the fixed lower rail in longitudinal direction for adjusting the longitudinal position of the vehicle seat as desired by the user. For reliably defining the end positions of the upper rail, end stops are used. In general the adjusting device shall be as light-weight as possible while ensuring a noise-free adjusting and a high mechanical stability, particularly in the event of a side crash and front crash, where high lateral and vertical loads act on the rails of the adjusting device. A stable support of the vehicle seat is desired in any longitudinal position of the upper rail, particularly also in the extreme positions, i.e. the full forward and full rearward position of the upper rail.
FIG. 1a shows a conventional upper rail 110 having a rectangular cross-section, comprising a base leg 111, a side wall 112 and a lateral bearing area 113 formed by a slanted leg of the profile. As shown in FIG. 1a, end stops 114 are punched out of the lateral bearing area 113 and bent upward. The adjusting device of FIG. 1b further comprises a lower rail 120 having a rectangular cross-section, comprising a bearing area 121, which together with the bearing area 113 of the upper rail 110 supports bearing members, such as steel balls or rollers, which may be accommodated in a retainer 122, such as a bearing cage, and serve for reducing friction between the two rails 110, 120 and ensuring a comfortable, noise-free and rattle-free adjustment of the upper rail 110 relative to the lower rail 120. By cooperation of the end stops 114 with the lower rail 120 the full forward position and full rearward position of the upper rail 110 is defined. Particularly, the end stops 114 together with retainer 122 abut against parts of the opposite lower rail 120 in the extreme positions. Thus, the total travel range of the adjusting device is limited by the fixed positions of the end stops 114 and is usually reduced to a distance shorter than the total length of the upper rail 110 and lower rail 120, respectively.
Instead of forming such end stops integrally with the respective rail and subsequent processing thereof, such as punching and bending, DE 102008012213 A1 discloses an end stop member of an adjusting device for longitudinal adjustment of a vehicle seat, which can be fixed as a separate member at an appropriate position on the upper or lower rail and suitably protrudes into the gap between the two rails to form an end stop at a respective extreme position of the adjusting device. The total travel range of the adjusting device is, however, limited by the fixed positions of the end stop members and cannot be extended beyond the total length of the upper rail and lower rail, respectively.
US 2011/0101194 A1 discloses another example of an adjusting device comprising end stop members that are fixed as separate members to one of the rails and protrude into the gap between the two rails so as to obstruct a further adjustment of the respective rail beyond the extreme position defined by the respective end stop.
US 2007/0158987 A1 discloses an adjusting device, wherein two oblong retainers are arranged between the lower rail and the upper rail along a longitudinal direction thereof, each comprising a central notch and expanded bearing portions at a front end and rear end of the oblong retainer, for accommodating and supporting steel balls serving as bearing members. The positions of the oblong retainers are fixed by bent, stationary tabs, which are punched out of the lateral bearing area of the upper rail and afterwards bent so as to obstruct a further adjustment of the oblong retainers beyond the positions defined by the tabs. The total travel range of the adjusting device is, however, limited by the fixed positions of the end stop members and cannot be extended.
In the market, there exists the need for adjusting devices enabling an extended travel range at a total length of the rails as short as possible, in order to enable as light-weight adjusting devices as possible, which nevertheless are stable enough to offer sufficient reliability in daily use and security in extreme situations, particularly in the event of a crash.